title: Resolving the TCA cycle and pentose-phosphate pathway of Clostridium acetobutylicum ATCC 824: Isotopomer analysis, in vitro activities and expression analysis.
abstract: Solventogenic clostridia are an important class of microorganisms that can produce various biofuels. One of the bottlenecks in engineering clostridia stems from the fact that central metabolic pathways remain poorly understood. Here, we utilized the power of (13) C-based isotopomer analysis to re-examine central metabolic pathways of Clostridium acetobutylicum ATCC 824. We demonstrate using [1,2-(13) C]glucose, MS analysis of intracellular metabolites, and enzymatic assays that C. acetobutylicum has a split TCA cycle where only Re-citrate synthase (CS) contributes to the production of α-ketoglutarate via citrate. Furthermore, we show that there is no carbon exchange between α-ketoglutarate and fumarate and that the oxidative pentose-phosphate pathway (oxPPP) is inactive. Dynamic gene expression analysis of the putative Re-CS gene (CAC0970), its operon, and all glycolysis, pentose-phosphate pathway, and TCA cycle genes identify genes and their degree of involvement in these core pathways that support the powerful primary metabolism of this industrial organism.
authors.affiliation: Department of Chemical Engineering, Metabolic Engineering and Systems Biology Laboratory, Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Crown
authors.forename: Dinesh C
authors.initials: DC
authors.lastname: Indurthi
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Ahn
authors.forename: Jungik
authors.initials: J
authors.lastname: Choi
authors.forename: Eleftherios T
authors.initials: ET
authors.lastname: Papoutsakis
authors.forename: Maciek R
authors.initials: MR
authors.lastname: Antoniewicz
mesh_terms: D002952:Citric Acid Cycle; D046969:Clostridium acetobutylicum / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D007656:Ketoglutaric Acids / Q000378:metabolism; D010427:Pentose Phosphate Pathway; D012997:Solvents
chemical_list: D007656:Ketoglutaric Acids; D012997:Solvents; D005947:Glucose